California startup NanoH20 has recently secured $15 Million to further develop a water purification membrane using 3D nano particles. The technology is claimed to dramatically increase the efficiency of reverse osmosis water filtering systems such as desalinization plants. Fresh water availability is one of the biggest issues facing 3rd world countries today, leading to starvation due to drought as well as disease due to consumption of contaminated water.
This may not be the Holy Grail in terms of being able to supply everyone with fresh water but it is another example of the dramatic technological advances being made with nano-tech materials research. If the material does what NanoH2O claims, look for them to be scooped up by someone in 2009.